Among brakes applied to a vehicle, there is a disc brake which serves to stop a wheel in which brake pads 14 grip a brake disc 12 which rotates along with the wheel as shown in FIGS. 1 and 2.
The disc brake includes a piston 15 mounted in a caliper 13 and pressed by a hydraulic pressure generated when a driver operates a brake pedal. The piston 15 pushes the brake pads 14 installed in the caliper 13 toward the brake disc 12. The brake pads 14 operated by the piston 15 grip the brake disc 12 which rotates along with the wheel in which the brake disc 12 and the wheel are connected to the same axle 11 in the caliper 13, thereby stopping rotation of the wheel by frictional force between the brake pads 14 and the brake disc 12.
When the braking operation is completed, it is necessary to separate the brake pads 14 from the brake disc 12 and to form gaps between the brake pads 14 and the brake disc 12, while the piston 15 is restored to an original position, such that the wheel may rotate without undergoing resistance due to contact between the brake pads 14 and the brake disc 12.
However, a drag phenomenon according to a run-out or change in thickness of the brake disc 12 occurs, that is, a phenomenon in which the brake pads 14 disturb the rotation of the brake disc 12 occurs since restoring force of the brake pads 14 is insufficient.
In order to prevent the above drag phenomenon, a pad liner 121 or 122 which serves as a spring is installed in the caliper 13 as shown in FIGS. 3 and 4. Thus, the pad liner 121 or 122 enables the brake pads 14 to be fully separated from the brake disc 12 when a hydraulic pressure for braking is removed therefrom.
However, the conventional pad liner 121 or 122 interferes with the brake disc 12 due to detachment from the caliper 13 and does not prevent foreign substances generated during the braking operation from being deposited therein or corrosion.
For example, the pad liner 121 shown in FIG. 3 supports the brake pads 14 by a constant load and provides restoring force to the brake pads 14. The pad liner 121 is fixed into the caliper 13 in a clip form or is coupled to the caliper 13 to form a locking protrusion at an upper portion thereof. However, when the pad liner 121 is not fully assembled to the caliper 13, the pad liner 121 is detached from the caliper 13, thereby interfering with the brake disc 12.
In addition, the pad liner 122 shown in FIG. 4 has elastic parts 122a so as to increase the restoring force of the brake pads 14 with respect to the caliper 13. However, when foreign substances are deposited in the elastic parts 122a, the pads 14 do not press the brake disc 12 during the braking operation. For this reason, the pad liner 122 cannot provide a sufficient braking force.
FIG. 5 illustrates decomposition of the pads and the pad liners in FIG. 4.